Explosion chamber for liquid break switches



Dec. 6,'l932. H. J. H. HUBER ET A1. 1,890,327

EXPLOSIONCHAHBER FOR LIQUID BREAK SWTGHES` Filed VApril 25, 1929 Her-man 4J. H.Huber,

. ChcxrLes Kellogg, b5 TheLr ttor'neg.

Patented Dec. 6, 1932 i PATENT orifice .UNITI-:D STATES JAH. HBER, OF UPPER DARBY, PENNSYLVANIA, AND CHARLES R. XELLOGG, OF SCOTIA, NEW YORK, ASSIGNOBS TO GENERAL ELECTRIC COMPANY, A CORPORA- TION F NEW YORK t EXPLOSION numana ron L IQUID :annex SWITCHES v v Application led April 25,

Our invention relates to electric switches ofthe type adapted to interrupt modern com- `mercial power circuits. More particularly `and the initial separation thereof takes place within an explosion chamber. Inasmuch as the explosion chamber members of such switches must be capable of withstanding y great internal pressure due to the sudden gas ormation therein when the switch is called upon to, interrupt a heavy load or short circuitit has been customary heretofore to construct the explosion chamber member of a metal having the requisite strength, such for -example as steel or bronze. As the metal chamber member at its point of support has beenin electrical connection with the fixed contact therein, the chamber member has been provided with a covering of insulation on both the inside and the outside to prevent the arc from whipping to the chamber walls.

`Atthe openingin the explosion chamber member through which the movable contact was withdrawn in the circuit interrupting `operation of the switch, a special throat bushing of 'insulation has been provided which connected with the aforesaid insulation covering. With the ever increasing voltages at which electric power is being transmitted increasing diiiculties have :arisen in the interruption of those circuits.- One of the problems which has given much trouble in the manufacture of these switches has been to prevent a breakdown of the insulation on j the metallic explosion chamber member par- `ticularly at or near the throat bushing and the resulting establishment of an arc be `tween the movable contact and, the metal of the explosion chamber member. This diiiiculty has been especially pronounced in the case of switches employed on certain 220 Kv. transmission lines where under particular conditions of phase displacement or other disturbance the actual voltage to which the i double the already high line voltage. no

insulation is subjected is approximately The object of our invention therefore isthe proa` Il. i

1929. serial No. 358,989.

vision of an electric switch having an im' proved explosion chamber member which shall overcome the problem of insulation breakdown mentioned above, and which shall also have the necessary mechanical strength to` withstand the great pressures produced therein.

Our invention will be/better undwstood from the following description taken m connection with the accompanying drawing, and its scope will be pointed out inthe appended claims.

Referring to the drawing, Fig. 1 is an elevational view partly in section, of a switch embodying our invention; Fig. 2 is a detail drawn to a larger scale of the explosion chamber member; and Fig. 3 is a similar view drawn at a slightly smaller scale showing a modified form.

The switch which we have illustrated by way of example in Fig. 1 as embodying our invention has an enclosing casing comprising the steel tank 1 containing the insulating liquid, such as oil, in which the contacts are immersed and the cover 2 securely bolted to the tank and supporting the contacts, mechanism, etc. Through the cover 2 extend the 4insulator bushings 3, shown as of the pil filled type such as are usually employed on switches for the higher voltages. Secured to the lower end of each insulator bushin is the adapt-er 4. by means of. which suita le adjustments may be made to compensate for variations in the bushings. Removably attached to the adapter is the fixed socket contact -5 and secured'to the flange 8 ci the adapter is the explosion chamber member or pot 7 hereinafter to be described. Between the two insulator bushings is the housing 8 containing parts oi the operating mechanism including the connection to the contact operating rod 9. The lower end of this rod is secured to the cross head l0 which supports and connects the two Contact rods ll.

ln accordance with our invention we have overcome the insulation breakdown dificrl ties mentioned above when switches having* been used to interrupt high voltage circuits 'insulated metallic explosion chambers have chamber member entirely of insulating material and constructed to have both the mechanical and the dielectric strength found necessary for such a member. As shown more clearly in Fig. 2 the explosion chamber member 7 has a tapering sidewall portion 12 which flares outwardly at its upper end to form the attaching ange portion 13 and which curves inwardly at its lower end to form the end portion 14 of the member. The explosion chamber member 7 we construct of built-up material composed'of la ers or laminations of paper or other suitab e insulating material impregnated with a resinous condensation product and cured while subjectedto the proper heat and pressure. We have found the well known phenol-formaldehyde type of resin to be a satisfactory condensation product for this purpose. The laminations extend continuously both circumferentially and longitudinally of the chamber member.

As indicated in the cross section shown in Fig. 2 the laminations in the side wall portion are parallel with the inner and outer surfaces thereof land extend continuously therefrom into both the attaching flange 13 and the end portion 14. By this continuity we obtain great strengtli for resisting the intense bursting pressures which may be produced within the chamber when heavy loads or short circuits are interrupted by the switch. Centrally of the end portion 14 is the flared guide opening or throat 15 for the movable contact rod 11. The laminations, it will be seen, ex-

tend continuously from the side wall portion 12 into the end portion 14 to the throat 15, a separate throat bushin thereby being unnecessary. A greater ength of the guide openin 15 is effected by building up that part o the end portion immediately surrounding the opening to a greater thickness. Likewise "additional material in the attaching flange 13 and at the junction thereof with the side wall portions results in greater strength at these points. In" Fig. 2 we have shown the explosion chamber member securedA to the flange 6 of the adapter by means of a series of bolts 16 the heads of which engage the metal ring 17. The inner edge of this ring is curved to conform to the fillet between the side wall and the flange of the explosion chamber member and serves both to distribute the pressure gf the bolt heads and to strengthen the mem- In the application of Charles F. Peterson, (Serial No. 358,072) filed concurrently herewith and assigned to the samefassignee as the present application, there is disclosed and claimed a method and an apparatus with which explosion chamber members of the kind described above have been successfully made.

In the modification illustrated b F i 3 the explosion chamber member 20 is a so o laminated insulating material, being similar in construction to the previouslyv described form. The securing flange in this form of our invention is in the form of an outwardly flaring conical extension 21 which is engaged by the securing ring 22 having a bevel inner face. Accordingly the metallic ring and not matethe conical extension 21 of insulatm rial is placed under tension due to hig pres-'- sures generated within the explosion member 20. By means of the bolts 23 passing through the flange 6 of the ada ter and the f l ring 22 theflange of the cham er membemI the previously described form in that it formsy The a depending lip 25 providing a somewhatlonger tapering' guide opening for the contact rod of the switch. In both forms of the explosion chamber member illustrated it will be noted that the attachin flange and the portion connecting it with t e side walls are somewhat thicker than the side walls, thereby obtaining reater 'mechanical strength at that part of t e structure. When found desirable that part of the structure may be strengthenedl still more b the substitution of canvas for Y paper to e ect the additional thickness.

In accordance with the above description it will be seen that we have produced an electric switch having an explos1on chamber constructed entirely of insulating material,`

thereby being devoid of all metal to which an arc mayy strike. The material of which we'construct the explosion chamber member in addition vto having a very high insulating value has by "reason 'of the particular one piece laminated construction disclosed a maximum mechanical strength to resist the bursting pressures to which the chamber is subjected in service. Y 1- -What I claim as new and desire to secure by Letters Patent of the United States, is:

1.. In an electric switch having relatively movable contacts arranged to be separated in an insulating liquid, an all-insulation explosion chamber pot surrounding one of said contacts and having a throat opening through which a coacting contact is withdrawn when said contacts are separated, said explosion chamber pot being a one-piece structure composed of built-up laminations of insulatin material extending longitudinally of an continuously throughout the wall structure of said pot so as to withstand high bursting preures.

2. In an electric switch having relatively movable contacts arranged to be separated in an insulatin liquid,` an explosion chamber pot immerse inlsaid liquid' and surroundin one of said contacts comprising a periphera securing iiangel ortion, a side wall portion and an end lWa l `portion having athroat opening through which a coacting contact is guided, said portions being continuous and forming a unitary 4structure composed of built-up laminations of insulating material arranged so that the laminations of one portion extend into theadjacent portion or portions. f

3. In an electric switch of the explosion chamber type, an explosion chamber pot having aunitary andcontinuous wall structure comprising a tapering side wall ortion lterminating in an outwardly exten ing securing flanveportion and in an end portion khaving a ared guide opening, said Wall structure composed of built-up laminations of fibrous material impregnated with a resinous condensation product arranged so as to extend longitudinally of said side wall portion and into said flange and end portions. In Wtnesswhereof, we have hereunto set our hands this 23rd day of April, 1929, and this 20th day of'A ril, 1929.

HER AN J. H. HUBER.

CHARLES' R. KELLGGG. 

